Posted
by
Unknown Lamer
on Tuesday May 22, 2012 @09:00AM
from the global-plot-to-drown-new-yorkers dept.

scibri writes "During the latter half of the twentieth century, global sea level rose by about 1.8 millimeters per year. The combined contribution from heating of the oceans, which makes the water expand, along with melting of ice caps and glaciers, is estimated to be 1.1 millimeters per year, which left some 0.7 millimeters per year unaccounted for. It seems that the effects of human water use on land could fill that gap. Researchers report in Nature Geoscience that land-based water storage could account for 0.77 millimeters per year, or 42%, of the observed sea-level rise between 1961 and 2003. The extraction of groundwater for irrigation and home and industrial use, with subsequent run-off to rivers and eventually to the oceans, represents the bulk of the contribution. It would be even worse if we weren't also locking up lots of water from rivers behind dams like the Hoover Dam."

It would be even worse if we weren't also locking up lots of water from rivers behind dams like the Hoover Dam

Even worse? Like a couple more millimeters! Evacuate NYC!

According to my calculations, 1.8 mm per year means about 3.5 inches in the 50 years they're talking about. They're not laughing in the Maldives, Florida or a number of low-lying coastal regions, such as, oh, yeah, Manhattan.

Except no one looks back at the 20th century and remembers the great sea level disaster. The sea rose 7" over the 20th century, with zero acceleration in rate until the satellites came online, and no one noticed for 90 years. (Which obviously proves satellites cause sea level rise. )

If you continue to just use the geologically stable tide gauges (as was used before satellite data became available) the rate of sea level change hasn't changed in 100 years.

Except no one looks back at the 20th century and remembers the great sea level disaster.

Ever hear of Venice? Of course Venice is also subsiding, but seven inches on top of that has made a big difference to them.

The problem with sea level rise in the short term isn't that suddenly you're city is drowned every day of the year. It's with the increase in frequency with which rare catastrophic events occur. Every coastal city has a high water level below which flooding effects are marginal and above which they are catastrophic (e.g. a levee is overtopped). How close waters commonly come to that mark determines the impact of a marginal increase in sea level.

Cities like Venice or New Orleans which are already prone to flooding are certainly affected by an 18 cm rise in mean sea level, although that effect isn't necessarily seen every year. Boston on the other hand was built to withstand 3-4m tides and has never had a major flood from the sea, so the 18 cm rise in the 20th C. had zero effect on it. If at some point in the future sea levels rise by a meter or so, flooding might become a common event in Boston. At that point a further 18 a cm rise would be very expensive to deal with.

The effect of sea level rise is not linear, and it's not uniform throughout the world. The effect depends on how a city is constructed and situated.

Now as to "geologically stable tide guages", if you knew anything about surveying you'd know that rather begs the question. In any case you can get any result you want by arbitrarily throwing out data; *mocking* data you'd prefer not to exist doesn't count as an argument.

The gist is that in Texas people have the right to use any beach even if it puts them close to a house, up to the vegetation line. The problem is when the vegetation line is moved by a heavy storm. Apparently one woman ended up having her home move from being on private property to being on public propert

Coral Atolls cannot suffer from sea level rise, they are the result of life living near the surface creating a deposit that itself builds the atoll. The Maldives will never suffer from gradual sea level rise. Charles Darwin himself discovered how Atolls remain above water. If these islands were bedrock, you might be right, but they're not. Atolls are essentially floating islands.

Results show that 86% of islands remained stable (43%) or increased in area (43%) over the timeframe of analysis. Largest decadal rates of increase in island area range between 0.1 to 5.6 hectares. Only 14% of study islands exhibited a net reduction in island area.

Despite small net changes in area, islands exhibited larger gross changes. This was expressed as changes in the planform configuration and position of islands on reef platforms. Modes of island change included: ocean shoreline displacement toward the lagoon; lagoon shoreline progradation; and, extension of the ends of elongate islands. Collectively these adjustments represent net lagoonward migration of islands in 65% of cases.

Results contradict existing paradigms of island response and have significant implications for the consideration of island stability under ongoing sea level rise in the central Pacific.

First, islands are geomorphologically persistent features on atoll reef platforms and can increase in island area despite sea level change....

The islands are created by the corals living in the waters. That limits the rate at which they can be "built" up to keep up with sea level rise. Also, other effects of rising CO2 levels, like warmer seas and ocean acidification may reduce the rate at which corals can build islands.

Using a 30-tank experimental system, we manipulated CO2 levels to simulate doubling and three- to fourfold increases [Intergovernmental Panel on Climate Change (IPCC) projection categories IV and VI] relative to present-day levels under cool and warm scenarios. Results indicated that high CO2 is a bleaching agent for corals and CCA under high irradiance, acting synergistically with warming to lower thermal bleaching thresholds.

Did they add the CO2 to the mixture on geologic timescales? If not, they cannot possibly be simulating the earth properly. Biological processes over eons trumps this simple experiment every time.

Sure, if you throw enough CO2 into the experiment in hours or days, you'll kill coral. However there's no possible way to do this to earths oceans within all of mankind's technology. If instead you're adding fractions of a percent of CO2 to the mix per century (as real life behaves), biology responds to neutralize

Perfectly "clean" rainwater should have a pH close to 7.0 -- being pure water. 5.6 is bordering on "acid rain". (I'll check my rainwater sisterns, but they've had a long time to settle.)

Yes, sea water is highly buffered. However, that buffer is not instant. Look at the small scale in my (freshwater) aquariums... they have carbonate buffers in there (a lot of it, in fact -- aragonite and commerical buffers) and the pH can still dip below 6.6. If I draw a sample for testing, sealed in the tube, the pH wil

I live in Florida on the water. I'm at 18.5' of elevation at the top of my bank and 22' at the lowest point of my door sill. At 1.8mm a year I'll worry about it in 3132.6 years when the water reaches the top of the bank...till then I'm just gonna chill with a cold one.

That article you linked to is about coastal erosion, where the soil holding up the cliff was washed away into the sea. What does this have to do with sea rise or anything else? And it wasn't talking about the 'annual change' of that particular coastline, but the fact that several feet of the ground between a particular apartment building and the ocean was washed away in a few days.

Instead of being modded insightful, you should be modded Off-topic instead.

You aren't very polite, and you aren't good at doing basic research. If you'd spent five minutes on Google, you might have found this [asce.org], which shows a change in the coastline of more than.5 meters over the last 146 years.

If you can't tell what continental drift and erosion has to do with sea-level rise, I don't know what to tell you. Continental drift means some coasts are growing an order of magnitude larger than the sea change. In other places, it is shrinking many times faster than sea level change.

Thus we see, for people who live on the coast, sea level rise of 1.8mm is a laughably small problem, when compared to the many other things they are facing.

Continental drift is not about coasts "growing" at all. Continental drift is exactly what it sounds like, and should therefore be self-explanatory. The "continents" are "drifting" (moving in other words). With some simple research, you would have found the definition if you couldn't deduce the meaning. US Geological Survey [usgs.gov]

Coastal erosion is where the "coasts" are "eroding" away. Ocean waves and currents are washing away soil and rock, moving the coastline (where the water meets the land) inward in s

Well I certainly don't think you would come up with that propaganda on your own! Though it would entertain me if you did.

It fascinates me that you think continental drift is not relevant in an article about sea rise. You are right, of course, continental drift is a relatively small issue compared to tsunamis....the point is, the ocean level rise is a relatively small issue compared to the you land being lost in a subduction zone. And it's a non-issue if your land is growing.

Well... Hoover Dam doesn't have that much water behind it anymore
Having just last week spent 15 minutes flying over the lake in a commercial jetliner, I am inclined to disagree with you. In fact, it is listed as the 25th largest lake in the United states out of almost a half million lakes.

After the drought conditions that have existed in the Colorado River drainage for the past decade Lake Mead is currently only 57% of its normal water storage and that's up a bit from a couple of years ago. Lake Powell behind Glen Canyon Dam is only 72% of full. Together they are around 18 million acre-feet below their full capacity.

An acre-foot of water is one acre of area covered by a foot of water. It is a common unit in the United States for measuring large volumes of water. One acre-foot is equal to 1233.48184 cubic meters or 325851.4 US gallons. Hogsheads vary is size but if you take it to be 63 gallons then an acre-foot is about 5,172 hogsheads. Troy ounces is a measure of mass, not volume.

"It would be even worse if we weren't also locking up lots of water from rivers behind dams like the Hoover Dam."
- Isn't the rate at which it leaves the lake the same as if the dam hadn't been there (with maybe the exception of evaporation...), just with a delay? My understanding was that dams affect latency but not throughput...

I think the water behind dams may have a higher evaporation rate. Though my understanding of the Colarado river and such, the bigger issue is that diversion for irrigation is leading to the river essentially drying up before it reaches the ocean.

Not quite. Dams actually meter the water out at a specific rate, but that rate is typically less than what would flow naturally. Hence, the giant wall of water being held back. When it rains, the level goes up and when it doesn't it (relatively slowly) drains out. If it rains too much, there is a mechanism to release more water in a controlled flow so it doesn't spill over the top. If the Hoover dam wasn't there the Colorado river would be much wider and deeper at that point, flooding a lot of developm

They claim the ocean is rising due to increased runoff from human activity, yet it's well known that most of the worlds major rivers are a shadow of their natural self by time they reach the ocean (if they get there at all). Perhaps stormwater drains are taking up the slack, but for the moment I'm left with two credible claims that on the surface appear to directly contradict each other?

Oh that I live to see this day, I agree with tmosley. Well played. That's basically the process, as far as I know - we extract loads of ground water - fresh one as well as fossil one. So sinks for water, particularly deep aquifers, play a lesser role in the water cycle. Since we force water to stay near the surface, evaporation increases and transport to the sea becomes increasingly important compared to transport into ground water. How, in the long term, ocean evaporation rates may change to counteract thi

This is a good study, and it gives me some real numbers to work with, and an alternative to the human production of water from combustion as a significant contributing factor to global warming. If humans are raising the ocean levels beyond simple thermal swelling, we have enough data to calculate the change in equilibrium between water vapor and water. I had never thought of fossil water as a major source of water vapor, but it makes perfect sense, and explains why areas far from manufacturing, city pavem

They claim the ocean is rising due to increased runoff from human activity, yet it's well known that most of the worlds major rivers are a shadow of their natural self by time they reach the ocean (if they get there at all)
Ah, well you see, it is humans fault that less water finds its way to the oceans AND it is humans fault that more, um...water, uh... finds its way to the oceans.

I suspect humans are pulling water out of the ground that would normally remain underground. That's causing a slow but measurable transfer of H2O into the ocean and higher levels.

As for "disappearing rivers" that's only true in the western desert areas. In the central and east part of the U.S. the rivers have greater flows than before and often set high tide records. This is a result of humans sucking water out of the ground & then dumping it into the rivers.

The sea levels have been rising since the last ice age, and for much of that time much faster than now. The volume of the ocean changes for many reasons. Those lands that are essentially at sea level are doomed anyway, no point in the sob stories of displaced natives as their land would be covered even without any alleged actions by man, if not now then in next few centuries. Better they move now before their population grows even bigger and more people are affected.

This also includes some prime U.S. real estate as well --- I for one would be very sad to lose the Outer Banks (North Caroline barrier islands), and losing them would have negative implications for the North Carolina coast during hurricane season.

This does create some interesting questions:

- could one divert water from the outflow of major rivers for and pump it up-hill to a reservoir which would replenish ground water?
- should cooling systems for nuclear power plants, rather than pump all w

re. Outer Banks: I don't think you'd lose their buffer characteristics overnight; you'd have to wait until they were under something like 30' of ocean. They're still there and able to temper/stop any storm surge from hurricanes.

re. aquifers: why would you want to pump it anywhere? You fill the aquifer with the water that is still uphill by damming it up while it's up there - it's less energy-intensive that way. Problem is (if Oregon is any indication), building a dam is politically impossible these days.

re: ground water: A big problem is that some aquifers (e.g. the Ogallala) span multiple states. Who gets to pay for, manage, and regulate that?

One more bit: In most of the Western US, water is a very touchy subject. Water rights and ownership is separate from property and mineral rights (e.g. you can often own the dirt, but not the water to be found in, under, or on it). Except for parts of Oregon and Washington, you will find water rights, ownership, and laws to be a byzantine and brain-hurting mess to sort through. That it works at all without physical violence breaking out is a miracle.

It's called Post-Glacial Rebound [wikipedia.org], the land was pushed down by the glaciers, it's still rising now that the ice is gone. And since water runs down hill the Great Lakes (among others) are draining.

I'm pretty sure he was saying that it always continues warming from one ice age until we hit the next. Whether we melt all the ice a hundred years sooner is unimportant in both the short and long term. In the medium term you have a bunch of people pissing and moaning because they got stuck with the changing real estate rather than their great-grandkids.

The ice is going to melt. We are going to have another ice age. There's not a damned thing anyone can do about it and it's probably not going to happen in my lifetime, so why should I give a fuck?

I think you mean hydrogen, Eventually Earth will be like Venus, the Sun's rays having split all the water molecules in the upper atmosphere and sent the H2 spinning off into space. On the scale your planning people will be busrting into flames in a few thousand years. OTOH you will have averted countless ice ages over the next billion years or so.

If we do the right thing and burn the H2 then there won't be any change in the total amount of water in the system, save for what is in H2 storage tanks.

This is obviously just another cry of "the sky is falling" from a bunch of alarmists pushing their anti-freedom agenda.

There's no credible evidence that this so-called "ground water" exists at all. Look down at your feet: The ground is made out of dirt. How do they supposedly turn all this dirt into water? Answer: They can't. Dirt is black, water is clear. You don't get one from the other. It's just common sense, people.

Brother, your indignation is most righteous! However, you must remind yourself of the Scripture!

Genesis 1:6 -- 'And God said, "Let there be a firmament in the midst of the waters, and let it separate the waters from the waters." 7 And God made the firmament and separated the waters which were under the firmament from the waters which were above the firmament.'

Let us not be the ones to disrupt the wisdom of His divine order by moving the waters from one side of the firmament to another!

About 27 percent of the irrigated land in the United States overlies this aquifer system, which yields about 30 percent of the nation's ground water used for irrigation. In addition, the aquifer system provides drinking water to 82 percent of the people who live within the aquifer boundary.

Depends where you are: The southwest US is already having serious water problems, while all the Great Lakes cities are doing just fine in terms of overall supply. It bothers me that anyone would think that growing turf grass in a desert was a good idea, but that is in fact what we're doing.

The relevant part in this shocking news is "0.77 millimeters per year", not "42% of recent sea level rise". How on earth does one measure 0.77 mm per year? When I watch the waves breaking against the sea shore this seems so far fetched.

The older method, still in use, is to use tide gauges. Basically, these are long cylinders placed below the water level, and thus are able to remain mostly unaffected by waves. Hundreds, if not thousands of measurements are taken electronically every day, and these measurements give a good measure of the water level at that location over the course of the year. According to Wikipedia, there are over 1700 tide gauges being used worldwide, so you wind up getting a good average of the worldwide sea level.

The newer method is to use satellite altimeters which use radar to give accurate measures of the altitude of the land or sea below them.

The two methods combined give millions of data points over the course of a year, and scientists have been taking measurements since the mid-1800's.

Despite what one may think, it's not quite like there are scientists on beaches around the world placing a new toothpick in the sand for each and every wave.

Old fashioned tidal gauges are very acurate if kept well maintained, a simple tube effectively removes the waves, larger ones use what is called a "stilling well" but the principle is the same as measureing the 'true' hieght of choppy bath water with a perspex tube. Having said that I'm pretty sure the 0.77mm/yr is a statistic, ie: the gradient of the trend over a number of decades or centuries in some areas. An (unexplained) three inch rise over 100yrs is certainly something that could be observed in histo

I was thinking that this might be mathematically silly as even though.77 millimeters per year isn't much the surface area of the ocean in VAST (131.6 million miles). But a quick calculation on Wolfram Alpha shows it'd only take 69,300,000 gallons of water or less than enough water to fill a supertanker. That sounds reasonable to me.

If the raise described is the volume of one supertanker, that means 1 supertanker filled with water would (fully dispersed) raise worldwide ocean levels by.77mm.

Sure, less weight for oil than water, so the total displacement for working supertankers is lower, but still... with the armada of supertankers around the world, this should be measurable effect in total.

It would be even worse if we weren't also locking up lots of water from rivers behind dams like the Hoover Dam.

I don't see why this matters much. If you released all of the dammed water, you'd have a one-time increase in ocean levels. So what? Dams control rivers, sure, but those rivers are still flowing and have been this entire time. Surely the throughput from that river over a relatively short period of time is far more significant than any amount of water dammed along that river.

To me, that statement is as silly as, "We'd have even more cars on the road if we weren't locking some of them up at red lights and intersections."

They certainly increase evaporation, and probably absorption of water back into the ground. Whether or not that amount of water is negligible or not is the question. Simply put, less water makes it to the ocean after a river is dammed than before.

How is this news for nerds? Hell, there is probably a good percent of the slash dot crowd that doesn't even bathe regularly... Really, the alarm over AGW is really not tech related unless any of the following: Its a _real_ crisis (just one little drowning?), 2. something that can be done, 3. or it is actually interesting in a nerdy kind of way...

If this were a real concern, beachfront property prices would be falling. Islands would be littered with For Sale signs. 1 mm over many decades doesn't mean squat

Photos from orbit will show earth looking more and more like a prune with all that sucking of water, oil & gas from below even as the surging tides flow in to fill the wrinkles that appear. The earth will turn in on itself and shrink like a raisin with the remaining ice caps to look like a tasty sugar frosting. The end will come when a giant spoon scoops up the planet and it is crushed by immense teeth and devoured in a potent mix of saliva and digestive juices. Or maybe I'm letting my imagination carry

There are other causes besides just melting ice caps and expanding water and man made activities. For instance, the Great Lakes in the US are rising. As they rise, the more and more water runs out of them and eventually finds its way to the sea. There are other large bodies of water with similar geological forces in play that have nothing to do with man's activity.

It seems like places like Venice were worried about rising water levels long before 20th century man started irrigated cropland and the like. I am not a climatologist or anything like that but it seems like an awfully simple model that only looks at melting ice, warming water and the rest is because of people.

Actually, I know that 1 of the great lakes (forget the one) is lower and the amount is approximately the amount taken out of it for freshwater use (farming is always a big water user.) I heard about the studies back when the Great Lake states were discussing a deal where they would forbid any other state from stealing water from the Lakes - which sounded a bit nuts to people up here but people in AZ just assume someday they'll get water from the Great Lakes like we were just next door. I followed the har

Actually, I know that 1 of the great lakes (forget the one) is lower and the amount is approximately the amount taken out of it for freshwater use (farming is always a big water user.) I heard about the studies back when the Great Lake states were discussing a deal where they would forbid any other state from stealing water from the Lakes - which sounded a bit nuts to people up here but people in AZ just assume someday they'll get water from the Great Lakes like we were just next door. I followed the hardly covered issue back then because having been in AZ, I know it was not crazy to the people wanting to make the deal. Thankfully our politicians opposed it (no lobby or media coverage) but when the time comes they'll easily change positions and undo past law if properly bribed.

Actually, the whole region around the Great Lakes is rising. It was compressed during the last iceage and has be returning to it's normal, decompressed state ever since. If it was simply water being taken out of the lakes for other use, then the level would be low everywhere. However, the one end has raised significantly (in geological terms) and has nothing to do with water usage. However, the water that was in the now lifted area has run out, ultimately into the ocean (through the normal channels).

It would be even worse if we weren't also locking up lots of water from rivers behind dams like the Hoover Dam.

How would that be? Dams don't make the water go away. Over time, the amount of water going into the reservoir equals the amount leaving, or else the water levels would either drop or overflow the dam. The only significant change I'd see is that dams increase the surface area of the water and would therefore raise evaporation, so some of the water that would normally go downstream would turn into atmospheric moisture instead. For global warming purposes, that's probably not a good thing. But would it actually have a non-negligible effect on ocean levels?

I wondered this too... so I went and read the linked original article, which quite clearly states:

"Artificial reservoirs, such as the Hoover Dam on the Colorado River and the Three Gorges Dam on the Yangtze River in China, have the opposite effect, locking up water that would otherwise flow into the seas."

But if there is one scientist who knows more about sea levels than anyone else in the world it is the Swedish geologist and physicist Nils-Axel MÃrner, formerly chairman of the INQUA International Commission on Sea Level Change. And the uncompromising verdict of Dr MÃrner, who for 35 years has been using every known scientific method to study sea levels all over the globe, is that all this talk about the sea rising is nothing but a colossal scare story.Despite fluctuations down as well as up, "the sea is not rising," he says. "It hasn't risen in 50 years." If there is any rise this century it will "not be more than 10cm (four inches), with an uncertainty of plus or minus 10cm". And quite apart from examining the hard evidence, he says, the elementary laws of physics (latent heat needed to melt ice) tell us that the apocalypse conjured up byAl Gore and Co could not possibly come about....When running the International Commission on Sea Level Change, he launched a special project on the Maldives, whose leaders have for 20 years been calling for vast sums of international aid to stave off disaster. Six times he and his expert team visited the islands, to confirm that the sea has not risen for half a century. Before announcing his findings, he offered to show the inhabitants a film explaining why they had nothing to worry about. The government refused to let it be shown.

But hey, we all know that "there is 100% consensus among the serious scientists on AGW", right?

"Despite fluctuations down as well as up, "the sea is not rising," he says. "It hasn't risen in 50 years." If there is any rise this century it will "not be more than 10cm (four inches), with an uncertainty of plus or minus 10cm".

So...he's basically saying that he has a mean rise somewhere just shy of 10cm, and an uncertainty of 10cm. That would, to a simple engineer like myself, suggest that sea levels ARE rising, and that they are rising at a rate which is somewhere between a negligible amount and 20cm over 100 years, or (wait for it) 2mm per year. TFS suggests that 1.8mm/yr is the annual average amount for the last fifty years. Presuming that there was no change - or a negligible one - from 1910-1960, that would average out to 0.9mm.yr.

That's 9cm in 100 years or 10% less than Dr MÃrner's "not more than" mean, and well within his +/- 10cm. band.

Mörner is not one of the serious scientists. I thought I recognized his name and looked him up at wikipedia. One of his previous achievements is winning the "Deceiver of the year" award for supporting dowsing.

But sea level rise due to global temperature should be offset by the associated decrease in the number of pirates [wikipedia.org]. As this number declines, the associated hull displacement contributing to sea level rise decreases, bringing the system back towards stability.

It never fails to amaze me how little we understand the systems that we are attempting to regulate. Possibly with serious unforeseen consequences.

Now you kids stay off my lawn! I'm doing my part to reduce sea level by watering it.

With all the earthquakes that happen undersea every year, the is some major ocean fllor remodeling going on. Of course the zero sum model that they are pushing also must mean that the ocean volume change because of tectonic shift is also zero sum.

A few thousand square mles of ocean floor raising a couple inches will have more of effect to sea level increases than all man made activity over the last ten thousand years.

I'm suprised that they haven't blamed hunting beavers in the 1700's for an increase in

If only there were some way for water in the oceans to be reclaimed - perhaps we could find some way to take water from the oceans, form them into big "clouds" and then have some sort of propuslion system (wind currents?) push them over dry patches of land and somehow have that water somehow drop from the sky onto the ground...

Hmmz, haven't calculated that, but I did calculate that Facebook is adding about 90% shit to the internet. Leaving 9% for twitter and 1% for 4chan. An outcome that suprised me to be honest. I would have expected twitter to be good for at least 11%.

Might want to ask the fish also. they see it as a major stumbling block. Or did, when they were around, but the Hoover dam is a substantial impediment to their reaching those spawning grounds, so they, well, gave up.

Other smaller dams did as much damage. Atlantic Salmon didn't need the extra tress, but this contributed to their becoming rare as they are now. I've caught my last Atlantic Salmon quite some time ago. Somehow the Pacific varieties have survived. Apparently the Japanese and Norweigans don'